The overall objectives of this project are: (1) To develop a quantitative truly reproducible model system for the study of carcinogenesis using the naturally occurring and ubiquitous carcinogenic mycotoxin, aflatoxin B1. (2) To study the interaction of the carcinogen with its specifc target cell, the hepatocyte. To this end, we have decided to employ two unique systems: First, we have developed a diploid rat liver hepatocyte culture for the study. No in vitro aflatoxin study to date, has utilized cultures of the specific target cell. Second, we are preparing these cultures from an isogenic rat, the Wistar/Lewis rat. This is done so as to eliminate histocompatibility problems when the in vitro transformed cells are injected back into the animal for testing tumor producing ability.